1. Field
The present disclosure relates generally to processing images and, in particular, to removing undesired features from images. Still more particularly, the present disclosure relates to a method and apparatus for removing undesired bright spots in an image.
2. Background
In some situations, undesired features may appear in images of scenes generated using a sensor system. For example, reflections of light off of surfaces in a scene may be detected by the sensor system and appear in the image generated for the scene as bright spots. Light may be reflected off of a surface when a ray of light hits the surface. This ray of light may also be referred to as an incident ray of light. Light may be reflected off of surfaces of various types of objects in a scene. These objects may include, for example, without limitation, people, buildings, aircraft, automobiles, leaves, manmade structures, and other suitable types of objects.
Reflections of light off of surfaces may be categorized as diffuse reflections or specular reflections. A diffuse reflection occurs when an incident ray of light is reflected off of a surface in multiple directions.
A specular reflection occurs when an incident ray of light is reflected off of a surface primarily in a single direction. In particular, a specular reflection occurs when the incident ray of light and the reflected ray of light have the same angle relative to an axis perpendicular to the surface. A specular reflection in a scene may appear as a bright spot in an image generated by a sensor system. A bright spot may be an area in the image in which the pixels in that area have intensity values greater than some selected threshold for brightness.
When the specular reflection is caused by light being reflected off of a large area of the surface, this reflection may be referred to as “glare”. When the specular reflection is light reflected off of a small facet of the surface, this reflection may be referred to as a “glint”. A glint may appear as a small feature in the image having a large intensity relative to the portion of the image surrounding the feature. In other words, a glint may appear as a small bright spot in the image. Typically, bright spots in images caused by glints are undesirable features in images.
When these types of undesirable features occur in an image, identifying and/or analyzing characteristics of objects in an image of a scene may be made more difficult than desired. For example, when an image is generated for an object, identification of the object may be more difficult than desired or may take more time than desired when undesired features are present in the image. These undesired features may make it more difficult to identify characteristics of the object that are used to identify the object itself.
As another example, if successive images are taken of the object at different times, those images may be compared to each other to determine whether changes are present in the object. The images may be used to determine whether inconsistencies may have occurred in subsequent images of the object. The presence of undesired features in these images, such as bright spots caused by glints, may make the identification of inconsistencies more difficult and time-consuming than desired.
Some currently available systems for reducing glints in images use high speed mechanical optics attached to imaging systems. These mechanical optics may include, for example, polarizers and optical filters. These types of mechanical optics may reduce the overall transmission of light through an imaging system. Reducing the transmission of light may reduce the amount of information provided in the images generated by the imaging system. Further, these types of mechanical optics may increase the weight and cost of imaging systems more than desired.
Therefore, it would be advantageous to have a method and apparatus that takes into account at least some of the issues discussed above as well as possibly other issues.